////////////////////////////////////////////////////////////////////////////////
/// DISCLAIMER
///
/// Copyright 2016 ArangoDB GmbH, Cologne, Germany
///
/// Licensed under the Apache License, Version 2.0 (the "License");
/// you may not use this file except in compliance with the License.
/// You may obtain a copy of the License at
///
///     http://www.apache.org/licenses/LICENSE-2.0
///
/// Unless required by applicable law or agreed to in writing, software
/// distributed under the License is distributed on an "AS IS" BASIS,
/// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
/// See the License for the specific language governing permissions and
/// limitations under the License.
///
/// Copyright holder is ArangoDB GmbH, Cologne, Germany
///
/// @author Andreas Streichardt
/// @author Frank Celler
////////////////////////////////////////////////////////////////////////////////

#include "Communicator.h"

#include "Basics/MutexLocker.h"
#include "Basics/socket-utils.h"
#include "Logger/Logger.h"
#include "Rest/HttpRequest.h"

using namespace arangodb;
using namespace arangodb::basics;
using namespace arangodb::communicator;

namespace {

#ifdef _WIN32
/* socketpair.c
Copyright 2007, 2010 by Nathan C. Myers <ncm@cantrip.org>
Redistribution and use in source and binary forms, with or without modification,
are permitted provided that the following conditions are met:
Redistributions of source code must retain the above copyright notice, this
list of conditions and the following disclaimer.
Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.
The name of the author must not be used to endorse or promote products
derived from this software without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
static int dumb_socketpair(SOCKET socks[2], int make_overlapped) {
  union {
    struct sockaddr_in inaddr;
    struct sockaddr addr;
  } a;
  memset(&a, 0, sizeof(a));  // clear memory before using the struct!

  SOCKET listener;
  int e;
  socklen_t addrlen = sizeof(a.inaddr);
  DWORD flags = (make_overlapped ? WSA_FLAG_OVERLAPPED : 0);
  int reuse = 1;

  if (socks == 0) {
    WSASetLastError(WSAEINVAL);
    return SOCKET_ERROR;
  }
  socks[0] = socks[1] = -1;

  listener = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
  if (listener == -1) return SOCKET_ERROR;

  memset(&a, 0, sizeof(a));
  a.inaddr.sin_family = AF_INET;
  a.inaddr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
  a.inaddr.sin_port = 0;

  for (;;) {
    if (setsockopt(listener, SOL_SOCKET, SO_REUSEADDR, (char*)&reuse,
                   (socklen_t)sizeof(reuse)) == -1)
      break;
    if (bind(listener, &a.addr, sizeof(a.inaddr)) == SOCKET_ERROR) break;

    memset(&a, 0, sizeof(a));
    if (getsockname(listener, &a.addr, &addrlen) == SOCKET_ERROR) break;
    // win32 getsockname may only set the port number, p=0.0005.
    // ( http://msdn.microsoft.com/library/ms738543.aspx ):
    a.inaddr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
    a.inaddr.sin_family = AF_INET;

    if (listen(listener, 1) == SOCKET_ERROR) break;

    socks[0] = WSASocketW(AF_INET, SOCK_STREAM, 0, NULL, 0, flags);
    if (socks[0] == -1) break;
    if (connect(socks[0], &a.addr, sizeof(a.inaddr)) == SOCKET_ERROR) break;

    socks[1] = accept(listener, NULL, NULL);
    if (socks[1] == -1) break;

    closesocket(listener);

    u_long mode = 1;
    int res = ioctlsocket(socks[0], FIONBIO, &mode);
    if (res != NO_ERROR) break;

    return 0;
  }

  e = WSAGetLastError();
  closesocket(listener);
  closesocket(socks[0]);
  closesocket(socks[1]);
  WSASetLastError(e);
  socks[0] = socks[1] = -1;
  return SOCKET_ERROR;
}
#endif

static std::string buildPrefix(Ticket ticketId) {
  return std::string("Communicator(") + std::to_string(ticketId) + ") // ";
}

static std::atomic_uint_fast64_t NEXT_TICKET_ID(static_cast<uint64_t>(1));
static std::vector<char> urlDotSeparators{'/', '#', '?'};
}  // namespace

Communicator::Communicator() : _curl(nullptr), _mc(CURLM_OK), _enabled(true) {
  curl_global_init(CURL_GLOBAL_ALL);
  _curl = curl_multi_init();

  /// start with unlimited, non-closing connection count.  ConnectionCount object will
  ///  moderate once requests start
  curl_multi_setopt(_curl, CURLMOPT_MAXCONNECTS, 0);  // default is -1, want unlimited

  if (_curl == nullptr) {
    THROW_ARANGO_EXCEPTION_MESSAGE(TRI_ERROR_OUT_OF_MEMORY,
                                   "unable to initialize curl");
  }

#ifdef _WIN32
  int err = dumb_socketpair(_socks, 0);
  if (err != 0) {
    throw std::runtime_error("Couldn't setup sockets. Error was: " + std::to_string(err));
  }
  _wakeup.fd = _socks[0];
#else
  int result = pipe(_fds);
  if (result != 0) {
    throw std::runtime_error("Couldn't setup pipe. Return code was: " +
                             std::to_string(result));
  }

  TRI_socket_t socket = {.fileDescriptor = _fds[0]};
  TRI_SetNonBlockingSocket(socket);
  _wakeup.fd = _fds[0];
#endif

  _wakeup.events = CURL_WAIT_POLLIN | CURL_WAIT_POLLPRI;
  // TODO: does _wakeup.revents has to be initialized here?
}

Communicator::~Communicator() {
  ::curl_multi_cleanup(_curl);
  ::curl_global_cleanup();
}

Ticket Communicator::addRequest(Destination&& destination,
                                std::unique_ptr<GeneralRequest> request,
                                Callbacks callbacks, Options options) {
  uint64_t id = NEXT_TICKET_ID.fetch_add(1, std::memory_order_seq_cst);
  TRI_ASSERT(request != nullptr);

  {
    MUTEX_LOCKER(guard, _newRequestsLock);
    _newRequests.emplace_back(
        NewRequest{destination, std::move(request), callbacks, options, id});
  }

  LOG_TOPIC(TRACE, Logger::COMMUNICATION)
      << "request to " << destination.url() << " has been put onto queue";
  // mop: just send \0 terminated empty string to wake up worker thread
#ifdef _WIN32
  ssize_t numBytes = send(_socks[1], "", 1, 0);
#else
  ssize_t numBytes = write(_fds[1], "", 1);
#endif

  if (numBytes != 1) {
    LOG_TOPIC(WARN, Logger::COMMUNICATION)
        << "Couldn't wake up pipe. numBytes was " + std::to_string(numBytes);
  }

  return Ticket{id};
}

int Communicator::work_once() {
  std::vector<NewRequest> newRequests;
  int connections;

  {
    MUTEX_LOCKER(guard, _newRequestsLock);
    newRequests.swap(_newRequests);
  }

  /// make sure there is enough room for every new request to get
  ///  an independent connection
  connections = connectionCount.newMaxConnections(newRequests.size());
  curl_multi_setopt(_curl, CURLMOPT_MAXCONNECTS, connections);

  for (auto& newRequest : newRequests) {
    createRequestInProgress(std::move(newRequest));
  }

  int stillRunning;
  _mc = curl_multi_perform(_curl, &stillRunning);
  if (_mc != CURLM_OK) {
    throw std::runtime_error(
        "Invalid curl multi result while performing! Result was " + std::to_string(_mc));
  }

  /// use stillRunning as high water mark for open connections needed.
  ///  curl/lib/multi.c uses stillRunning * 4 to estimate connections retained,
  ///  starting with *2
  connectionCount.updateMaxConnections(stillRunning * 2);

  // handle all messages received
  CURLMsg* msg = nullptr;
  int msgsLeft = 0;

  while ((msg = curl_multi_info_read(_curl, &msgsLeft))) {
    if (msg->msg == CURLMSG_DONE) {
      CURL* handle = msg->easy_handle;

      handleResult(handle, msg->data.result);
    }
  }
  return stillRunning;
}

void Communicator::wait() {
  static int const MAX_WAIT_MSECS = 1000;  // wait max. 1 seconds

  int numFds;  // not used here
  int res = curl_multi_wait(_curl, &_wakeup, 1, MAX_WAIT_MSECS, &numFds);
  if (res != CURLM_OK) {
    throw std::runtime_error(
        "Invalid curl multi result while waiting! Result was " + std::to_string(res));
  }

  // drain the pipe
  char a[16];
#ifdef _WIN32
  while (0 < recv(_socks[0], a, sizeof(a), 0)) {
  }
#else
  while (0 < read(_fds[0], a, sizeof(a))) {
  }
#endif
}

// -----------------------------------------------------------------------------
// --SECTION--                                                   private methods
// -----------------------------------------------------------------------------

void Communicator::createRequestInProgress(NewRequest&& newRequest) {
  if (!_enabled) {
    LOG_TOPIC(DEBUG, arangodb::Logger::COMMUNICATION)
        << "Request to  '" << newRequest._destination.url()
        << "' was not even started because communication is disabled";
    callErrorFn(newRequest._ticketId, newRequest._destination,
                newRequest._callbacks, TRI_COMMUNICATOR_DISABLED, {nullptr});
    return;
  }

  // mop: the curl handle will be managed safely via unique_ptr and hold
  // ownership for rip
  auto rip = new RequestInProgress(newRequest._destination, newRequest._callbacks,
                                   newRequest._ticketId, newRequest._options,
                                   std::move(newRequest._request));

  auto handleInProgress = std::make_shared<CurlHandle>(rip);

  auto request = (HttpRequest*)handleInProgress->_rip->_request.get();

  CURL* handle = handleInProgress->_handle;
  struct curl_slist* requestHeaders = nullptr;

  // CURLOPT_POSTFIELDS has to be set for CURLOPT_POST, even if the body is
  // empty.
  // Otherwise, curl uses CURLOPT_READFUNCTION on CURLOPT_READDATA, which
  // default to fread and stdin, respectively: this can cause curl to wait
  // indefinitely.
  if (request->body().length() > 0 || request->requestType() == RequestType::POST) {
    curl_easy_setopt(handle, CURLOPT_POSTFIELDS, request->body().data());
    curl_easy_setopt(handle, CURLOPT_POSTFIELDSIZE, request->body().length());
  }

  // We still omit the content type on empty bodies.
  if (request->body().length() > 0) {
    switch (request->contentType()) {
      case ContentType::UNSET:
      case ContentType::CUSTOM:
      case ContentType::VPACK:
      case ContentType::DUMP:
        break;
      case ContentType::JSON:
        requestHeaders =
            curl_slist_append(requestHeaders, "Content-Type: application/json");
        break;
      case ContentType::HTML:
        requestHeaders =
            curl_slist_append(requestHeaders, "Content-Type: text/html");
        break;
      case ContentType::TEXT:
        requestHeaders =
            curl_slist_append(requestHeaders, "Content-Type: text/plain");
        break;
    }
  }

  if (request->requestType() == RequestType::POST ||
      request->requestType() == RequestType::PUT) {
    // work around curl's Expect-100 Continue obsession
    // by sending an empty "Expect:" header
    // this tells curl to not send its "Expect: 100-continue" header
    requestHeaders = curl_slist_append(requestHeaders, "Expect:");
  }

  std::string thisHeader;
  for (auto const& header : request->headers()) {
    thisHeader.reserve(header.first.size() + header.second.size() + 2);
    thisHeader.append(header.first);
    thisHeader.append(": ", 2);
    thisHeader.append(header.second);
    requestHeaders = curl_slist_append(requestHeaders, thisHeader.c_str());

    thisHeader.clear();
  }

  std::string url = createSafeDottedCurlUrl(newRequest._destination.url());
  handleInProgress->_rip->_requestHeaders = requestHeaders;
  curl_easy_setopt(handle, CURLOPT_HTTPHEADER, requestHeaders);
  curl_easy_setopt(handle, CURLOPT_URL, url.c_str());
  curl_easy_setopt(handle, CURLOPT_PROXY, "");

  // the xfer/progress options are only used to handle request abortions
  curl_easy_setopt(handle, CURLOPT_NOPROGRESS, 0L);
  curl_easy_setopt(handle, CURLOPT_XFERINFOFUNCTION, Communicator::curlProgress);
  curl_easy_setopt(handle, CURLOPT_XFERINFODATA, handleInProgress->_rip.get());

  curl_easy_setopt(handle, CURLOPT_WRITEFUNCTION, Communicator::readBody);
  curl_easy_setopt(handle, CURLOPT_WRITEDATA, handleInProgress->_rip.get());
  curl_easy_setopt(handle, CURLOPT_HEADERFUNCTION, Communicator::readHeaders);
  curl_easy_setopt(handle, CURLOPT_HEADERDATA, handleInProgress->_rip.get());
  curl_easy_setopt(handle, CURLOPT_ERRORBUFFER, handleInProgress->_rip.get()->_errorBuffer);

  // mop: XXX :S CURLE 51 and 60...
  curl_easy_setopt(handle, CURLOPT_SSL_VERIFYPEER, 0L);
  curl_easy_setopt(handle, CURLOPT_SSL_VERIFYHOST, 0L);

  if (Logger::isEnabled(LogLevel::DEBUG, Logger::COMMUNICATION)) {
    // the logging caused by debugging is extremely expensive. only turn it on
    // when we really want it
    curl_easy_setopt(handle, CURLOPT_DEBUGFUNCTION, Communicator::curlDebug);
    curl_easy_setopt(handle, CURLOPT_DEBUGDATA, handleInProgress->_rip.get());
    curl_easy_setopt(handle, CURLOPT_VERBOSE, 1L);
  }

  long connectTimeout = static_cast<long>(newRequest._options.connectionTimeout);
  // mop: although curl is offering a MS scale connecttimeout this gets ignored
  // in at least 7.50.3
  // in doubt change the timeout to _MS below and hardcode it to 999 and see if
  // the requests immediately fail
  // if not this hack can go away
  if (connectTimeout <= 7) {
    // matthewv: previously arangod default was 1.  libcurl flushes its DNS cache
    //  every 60 seconds.  Tests showed DNS packets lost under high load. libcurl
    //  retries DNS after 5 seconds.  7 seconds allows for one retry plus a little padding.
    connectTimeout = 7;
  }

  curl_easy_setopt(handle, CURLOPT_TIMEOUT_MS,
                   static_cast<long>(newRequest._options.requestTimeout * 1000));
  curl_easy_setopt(handle, CURLOPT_CONNECTTIMEOUT, connectTimeout);

  switch (request->requestType()) {
    case RequestType::POST:
      curl_easy_setopt(handle, CURLOPT_POST, 1);
      break;
    case RequestType::PUT:
      // mop: apparently CURLOPT_PUT implies more stuff in curl
      // (for example it adds an expect 100 header)
      // this is not what we want so we make it a custom request
      curl_easy_setopt(handle, CURLOPT_CUSTOMREQUEST, "PUT");
      break;
    case RequestType::DELETE_REQ:
      curl_easy_setopt(handle, CURLOPT_CUSTOMREQUEST, "DELETE");
      break;
    case RequestType::HEAD:
      curl_easy_setopt(handle, CURLOPT_CUSTOMREQUEST, "HEAD");
      break;
    case RequestType::PATCH:
      curl_easy_setopt(handle, CURLOPT_CUSTOMREQUEST, "PATCH");
      break;
    case RequestType::OPTIONS:
      curl_easy_setopt(handle, CURLOPT_CUSTOMREQUEST, "OPTIONS");
      break;
    case RequestType::GET:
      break;
    case RequestType::VSTREAM_CRED:
    case RequestType::VSTREAM_REGISTER:
    case RequestType::VSTREAM_STATUS:
    case RequestType::ILLEGAL:
      throw std::runtime_error("Invalid request type " +
                               GeneralRequest::translateMethod(request->requestType()));
      break;
  }

  handleInProgress->_rip->_startTime = TRI_microtime();

  {
    MUTEX_LOCKER(guard, _handlesLock);
    // ticketId is produced by adding to an atomic counter, so each
    // ticketId should occur only once. adding to the map should
    // always succeed (or throw an exception in case of OOM). but it
    // should never happen that the key for the ticketId already exists
    // in the map
    auto result =
        _handlesInProgress.emplace(newRequest._ticketId, std::move(handleInProgress));
    TRI_ASSERT(result.second);
  }
  curl_multi_add_handle(_curl, handle);
}

/// new code using lambda and Scheduler
void Communicator::handleResult(CURL* handle, CURLcode rc) {
  curl_multi_remove_handle(_curl, handle);

  RequestInProgress* rip = nullptr;
  curl_easy_getinfo(handle, CURLINFO_PRIVATE, &rip);
  if (rip == nullptr) {
    return;
  }

  // unclear if this would be safe on another thread.  Leaving here.
  if (rip->_options._curlRcFn) {
    (*rip->_options._curlRcFn)(rc);
  }

  std::shared_ptr<CurlHandle> curlHandle;

  {
    MUTEX_LOCKER(guard, _handlesLock);
    auto inProgress = _handlesInProgress.find(rip->_ticketId);
    if (_handlesInProgress.end() != inProgress) {
      curlHandle = (*inProgress).second->getSharedPtr();
      _handlesInProgress.erase(rip->_ticketId);
    }
  }

  if (curlHandle) {
    // defensive code:  intentionally not passing "this".  There is a
    //   possibility that Scheduler will execute the code after Communicator
    //   object destroyed.  use shared_from_this() if ever essential.
    rip->_callbacks._scheduleMe([curlHandle, handle, rc, rip](bool) {  // lamda rewrite starts
      double connectTime = 0.0;
      LOG_TOPIC(TRACE, Logger::COMMUNICATION)
          << ::buildPrefix(rip->_ticketId) << "curl rc is : " << rc << " after "
          << Logger::FIXED(TRI_microtime() - rip->_startTime) << " s";

      if (CURLE_OPERATION_TIMEDOUT == rc) {
        curl_easy_getinfo(handle, CURLINFO_CONNECT_TIME, &connectTime);
        LOG_TOPIC(TRACE, Logger::COMMUNICATION)
            << ::buildPrefix(rip->_ticketId) << "CURLINFO_CONNECT_TIME is " << connectTime;
      }  // if

      if (strlen(rip->_errorBuffer) != 0) {
        LOG_TOPIC(TRACE, Logger::COMMUNICATION)
            << ::buildPrefix(rip->_ticketId)
            << "curl error details: " << rip->_errorBuffer;
      }

      double namelookup;
      curl_easy_getinfo(handle, CURLINFO_NAMELOOKUP_TIME, &namelookup);

      if (5.0 <= namelookup) {
        LOG_TOPIC(WARN, arangodb::Logger::FIXME)
            << "libcurl DNS lookup took " << namelookup
            << " seconds.  Consider using static IP addresses.";
      }

      switch (rc) {
        case CURLE_OK: {
          long httpStatusCode = 200;
          curl_easy_getinfo(handle, CURLINFO_RESPONSE_CODE, &httpStatusCode);

          std::unique_ptr<GeneralResponse> response(
              new HttpResponse(static_cast<ResponseCode>(httpStatusCode)));

          transformResult(handle, std::move(rip->_responseHeaders),
                          std::move(rip->_responseBody),
                          static_cast<HttpResponse*>(response.get()));

          if (httpStatusCode < 400) {
            callSuccessFn(rip->_ticketId, rip->_destination, rip->_callbacks,
                          std::move(response));
          } else {
            callErrorFn(rip, httpStatusCode, std::move(response));
          }
          break;
        }
        case CURLE_COULDNT_CONNECT:
        case CURLE_SSL_CONNECT_ERROR:
        case CURLE_COULDNT_RESOLVE_HOST:
        case CURLE_URL_MALFORMAT:
        case CURLE_SEND_ERROR:
          callErrorFn(rip, TRI_SIMPLE_CLIENT_COULD_NOT_CONNECT, {nullptr});
          break;
        case CURLE_OPERATION_TIMEDOUT:
        case CURLE_RECV_ERROR:
        case CURLE_GOT_NOTHING:
          if (rip->_aborted || (CURLE_OPERATION_TIMEDOUT == rc && 0.0 == connectTime)) {
            callErrorFn(rip, TRI_COMMUNICATOR_REQUEST_ABORTED, {nullptr});
          } else {
            callErrorFn(rip, TRI_ERROR_CLUSTER_TIMEOUT, {nullptr});
          }
          break;
        case CURLE_WRITE_ERROR:
          if (rip->_aborted) {
            callErrorFn(rip, TRI_COMMUNICATOR_REQUEST_ABORTED, {nullptr});
          } else {
            LOG_TOPIC(ERR, arangodb::Logger::FIXME)
                << "got a write error from curl but request was not aborted";
            callErrorFn(rip, TRI_ERROR_INTERNAL, {nullptr});
          }
          break;
        case CURLE_ABORTED_BY_CALLBACK:
          TRI_ASSERT(rip->_aborted);
          callErrorFn(rip, TRI_COMMUNICATOR_REQUEST_ABORTED, {nullptr});
          break;
        default:
          LOG_TOPIC(ERR, arangodb::Logger::FIXME) << "curl return " << rc;
          callErrorFn(rip, TRI_ERROR_INTERNAL, {nullptr});
          break;
      }

    });  // lambda rewrite ends
  } else {
    LOG_TOPIC(ERR, Logger::COMMUNICATION)
        << "In progress id not found via _handlesInProgress.find("
        << rip->_ticketId << ")";
  }
}

void Communicator::transformResult(CURL* handle, HeadersInProgress&& responseHeaders,
                                   std::unique_ptr<StringBuffer> responseBody,
                                   HttpResponse* response) {
  response->body().swap(responseBody.get());
  response->setHeaders(std::move(responseHeaders));
}

size_t Communicator::readBody(void* data, size_t size, size_t nitems, void* userp) {
  RequestInProgress* rip = (struct RequestInProgress*)userp;
  if (rip->_aborted) {
    return 0;
  }
  size_t realsize = size * nitems;
  try {
    rip->_responseBody->appendText((char*)data, realsize);
    return realsize;
  } catch (std::bad_alloc const&) {
    return 0;
  }
}

void Communicator::logHttpBody(std::string const& prefix, std::string const& data) {
  std::string::size_type n = 0;
  while (n < data.length()) {
    LOG_TOPIC(DEBUG, Logger::COMMUNICATION) << prefix << " " << data.substr(n, 80);
    n += 80;
  }
}

void Communicator::logHttpHeaders(std::string const& prefix, std::string const& headerData) {
  std::string::size_type last = 0;
  std::string::size_type n;
  while (true) {
    n = headerData.find("\r\n", last);
    if (n == std::string::npos) {
      break;
    }
    LOG_TOPIC(DEBUG, Logger::COMMUNICATION)
        << prefix << " " << headerData.substr(last, n - last);
    last = n + 2;
  }
}

int Communicator::curlProgress(void* userptr, curl_off_t dltotal, curl_off_t dlnow,
                               curl_off_t ultotal, curl_off_t ulnow) {
  RequestInProgress* rip = (struct RequestInProgress*)userptr;
  return (int)rip->_aborted;
}

int Communicator::curlDebug(CURL* handle, curl_infotype type, char* data,
                            size_t size, void* userptr) {
  arangodb::communicator::RequestInProgress* request = nullptr;
  curl_easy_getinfo(handle, CURLINFO_PRIVATE, &request);
  TRI_ASSERT(request != nullptr);
  TRI_ASSERT(data != nullptr);

  std::string dataStr(data, size);
  std::string prefix(::buildPrefix(request->_ticketId));

  switch (type) {
    case CURLINFO_TEXT:
      LOG_TOPIC(TRACE, Logger::COMMUNICATION) << prefix << "Text: " << dataStr;
      break;
    case CURLINFO_HEADER_OUT:
      logHttpHeaders(prefix + "Header >>", dataStr);
      break;
    case CURLINFO_HEADER_IN:
      logHttpHeaders(prefix + "Header <<", dataStr);
      break;
    case CURLINFO_DATA_OUT:
      logHttpBody(prefix + "Body >>", dataStr);
      break;
    case CURLINFO_DATA_IN:
      logHttpBody(prefix + "Body <<", dataStr);
      break;
    case CURLINFO_SSL_DATA_OUT:
      LOG_TOPIC(TRACE, Logger::COMMUNICATION)
          << prefix << "SSL outgoing data of size " << std::to_string(size);
      break;
    case CURLINFO_SSL_DATA_IN:
      LOG_TOPIC(TRACE, Logger::COMMUNICATION)
          << prefix << "SSL incoming data of size " << std::to_string(size);
      break;
    case CURLINFO_END:
      break;
  }
  return 0;
}

size_t Communicator::readHeaders(char* buffer, size_t size, size_t nitems, void* userptr) {
  size_t realsize = size * nitems;
  RequestInProgress* rip = (struct RequestInProgress*)userptr;
  if (rip->_aborted) {
    return 0;
  }

  std::string const header(buffer, realsize);
  size_t pivot = header.find(':');
  if (pivot != std::string::npos) {
    // mop: hmm response needs lowercased headers
    std::string headerKey =
        basics::StringUtils::tolower(std::string(header.c_str(), pivot));
    rip->_responseHeaders.emplace(headerKey,
                                  header.substr(pivot + 2, header.length() - pivot - 4));
  }
  return realsize;
}

std::string Communicator::createSafeDottedCurlUrl(std::string const& originalUrl) {
  std::string url;
  url.reserve(originalUrl.length());

  size_t length = originalUrl.length();
  size_t currentFind = 0;
  std::size_t found;

  while ((found = originalUrl.find("/.", currentFind)) != std::string::npos) {
    if (found + 2 == length) {
      url += originalUrl.substr(currentFind, found - currentFind) + "/%2E";
    } else if (std::find(urlDotSeparators.begin(), urlDotSeparators.end(),
                         originalUrl.at(found + 2)) != urlDotSeparators.end()) {
      url += originalUrl.substr(currentFind, found - currentFind) + "/%2E";
    } else {
      url += originalUrl.substr(currentFind, found - currentFind) + "/.";
    }
    currentFind = found + 2;
  }
  url += originalUrl.substr(currentFind);
  return url;
}

void Communicator::abortRequest(Ticket ticketId) {
  MUTEX_LOCKER(guard, _handlesLock);

  abortRequestInternal(ticketId);
}

void Communicator::abortRequests() {
  MUTEX_LOCKER(guard, _handlesLock);

  for (auto& request : requestsInProgress()) {
    abortRequestInternal(request->_ticketId);
  }
}

// needs _handlesLock!
std::vector<RequestInProgress const*> Communicator::requestsInProgress() {
  _handlesLock.assertLockedByCurrentThread();

  std::vector<RequestInProgress const*> vec;
  vec.reserve(_handlesInProgress.size());

  for (auto& handle : _handlesInProgress) {
    RequestInProgress* rip = nullptr;
    curl_easy_getinfo(handle.second->_handle, CURLINFO_PRIVATE, &rip);
    TRI_ASSERT(rip != nullptr);
    vec.push_back(rip);
  }
  return vec;
}

// needs _handlesLock!
void Communicator::abortRequestInternal(Ticket ticketId) {
  _handlesLock.assertLockedByCurrentThread();

  auto handle = _handlesInProgress.find(ticketId);
  if (handle == _handlesInProgress.end()) {
    return;
  }

  LOG_TOPIC(WARN, Logger::REQUESTS)
      << ::buildPrefix(handle->second->_rip->_ticketId)
      << "aborting request to " << handle->second->_rip->_destination.url();
  handle->second->_rip->_aborted = true;
}

void Communicator::callErrorFn(RequestInProgress* rip, int const& errorCode,
                               std::unique_ptr<GeneralResponse> response) {
  callErrorFn(rip->_ticketId, rip->_destination, rip->_callbacks, errorCode,
              std::move(response));
}

void Communicator::callErrorFn(Ticket const& ticketId, Destination const& destination,
                               Callbacks const& callbacks, int const& errorCode,
                               std::unique_ptr<GeneralResponse> response) {
  auto start = TRI_microtime();
  callbacks._onError(errorCode, std::move(response));
  // callbacks are executed from the curl loop..if they take a long time this
  // blocks all traffic! implement an async solution in that case!
  auto total = TRI_microtime() - start;

  if (total > CALLBACK_WARN_TIME) {
    LOG_TOPIC(WARN, Logger::COMMUNICATION)
        << ::buildPrefix(ticketId) << "error callback for request to "
        << destination.url() << " took " << total << "s";
  }
}

void Communicator::callSuccessFn(Ticket const& ticketId, Destination const& destination,
                                 Callbacks const& callbacks,
                                 std::unique_ptr<GeneralResponse> response) {
  // ALMOST the same code as in callErrorFn. just almost so I did copy paste
  // could be generalized but probably that code would be even more verbose
  auto start = TRI_microtime();
  callbacks._onSuccess(std::move(response));
  // callbacks are executed from the curl loop..if they take a long time this
  // blocks all traffic! implement an async solution in that case!
  auto total = TRI_microtime() - start;

  if (total > CALLBACK_WARN_TIME) {
    LOG_TOPIC(WARN, Logger::COMMUNICATION)
        << ::buildPrefix(ticketId) << "success callback for request to "
        << destination.url() << " took " << (total) << "s";
  }
}